Dispensing device for fluid substances

ABSTRACT

A dispensing device for fluid substances, including a pushbutton in which a chamber is provided housing a piston, the piston being loaded by an elastic mechanism to urge a front projecting appendix thereof into a dispensing hole for the substance, to hence sealedly close the hole, the pushbutton presenting a seat enabling a hollow stem to be coupled therethrough through which the pressurized substance is fed to the device. In the chamber there is housed an at least partially cylindrical member in an interior of which the piston slides, in the member there being provided at least one passageway opening to the front of the piston and communicating with a bore of the stem when the device is positioned on the pump.

The present invention relates to a dispensing device for fluidsubstances.

More particularly it relates to a dispensing device for fluid substancesboth in the form of cream and in the form of less viscous products suchas sprays, deodorants and the like.

In the known art a pushbutton is fixed to a hollow stem projecting froma container. Channels connecting the stem bore to a product dispensinghole are provided in the pushbutton. When dispensing is required,pressurized fluid withdrawn from a container is fed into the stem bore.Downstream of the stem there can be provided either a conventional pumpoperated by pressing the pushbutton, or a valve which is normally closedbut opens on pressing the pushbutton; in this latter case the vesselcontaining the substance to be dispensed must be under pressure.

This known art has the drawback that on termination of a dispensingoperation, all the residual product in the stem and in the pushbuttonconduits upstream of the dispensing hole is in contact with air; it cantherefore dry out or deteriorate and block the pump or valve and henceprevent correct product dispensing on subsequent use.

To obviate these known problems devices have been conceived such asthose described in EP0803294. That document describes a dispensingdevice comprising a dispensing pushbutton in which a piston is providedfrom which there projects a stem which when in the non-dispensingposition closes the dispensing hole. In this manner the productcontained in the stem and in the conduits provided within the pushbuttonis isolated from the air, the device hence being not subject tomalfunction deriving from incrustations which can form in said conduits.

However the aforesaid device (as in the case of many others present inthe known art) presents considerable drawbacks.

It is extremely difficult to mould the pushbutton, usually of plastic,because considerable thickness changes are present in proximity to thejoint between the chamber in which the piston slides and the cylindricalportion by which the pushbutton fits onto the stem. These thicknessvariations generate residual stresses in the moulding, leading toovalization in that region in which the piston is housed and slides.

This creates considerable problems for the seal between the piston lipand that conduit surface along which the piston slides.

An object of the present invention is therefore to provide a dispensingdevice which represents an improvement over the known art, and which inparticular overcomes the sealing problems present in the aforedescribedsolutions.

A further object of the present invention is to provide a device ofsimpler construction which enables the piston to operate and slide in anoptimal manner.

These and other objects are attained by a dispensing device for fluidsubstances formed in accordance with the technical teachings of theaccompanying claims.

Further characteristics and advantages of the invention will be apparentfrom the description of a preferred but non-exclusive embodiment of thedispensing device for fluid substances illustrated by way ofnon-limiting example in the accompanying drawings, in which:

FIG. 1 is a section through a device of the present invention in anon-dispensing position;

FIG. 2 is a section through the device of FIG. 1 in a dispensingposition;

FIG. 3 is a section through an alternative embodiment of the device ofthe present invention in a non-dispensing position; and

FIG. 4 is a section through the device of FIG. 3 in a dispensingposition.

With reference to said figures, these show a dispensing device indicatedoverall by the reference numeral 1.

It comprises a pushbutton formed preferably of plastic material bymoulding. A transverse chamber 3 presenting a frontal aperture 5 isprovided in its interior. An annular seat 6 is provided on the end 4 ofthe chamber 3, from which end there projects an abutment 7 the use ofwhich is clarified hereinafter. In the end there is also provided an airpassageway 8 communicating with the outside.

The pushbutton 2 comprises a seat 9, in the wall of which there is anannular groove 10. This seat 9 is arranged to receive and clamp by meansof the groove a hollow stem (not shown) through which the substance tobe dispensed is fed to said device. This substance passes through thestem bore under pressure. Hence the stem can be either that of aconventional dispensed pump or that for operating a valve associatedwith a pressurized vessel of known type. A member 11 for closing thechamber 3 is fitted into the chamber 3. The member 11 presents acylindrical portion 11 a, preferably of circular cross-section, whichfits onto the end of the chamber 3, namely into the annular seat 6.Interference is provided between the annular seat 6 and the cylindricalportion 11 a to ensure a perfect seal between the parts. Annularprojections can be provided on the surfaces of the annular seat toimprove the seal between the seat and the member 11.

The member 11 also presents a widened front portion 11 b carrying at itsend a dispensing hole 15 provided axially to the member 11. A piston 12movable against an elastic means (specifically a spring) is presentwithin the cylindrical portion 11 a.

On its front part the piston 12 presents a first lip 13 arranged to sealagainst the cylindrical portion 11 a, and a rear second lip 14 havingmerely a guide function in the illustrated example. The piston alsopresents, projecting frontally from it, an appendix 16 for sealedlyclosing the hole 15 when inserted therein. Essentially thepiston/appendix combination forms a valving element for the hole 15. Thespring 14 is specifically positioned between the piston 12 and the endof the chamber 3 in such a manner as to urge the appendix 16 into thehole 15.

The member 11 presents a passageway 22 which connects the front part ofthe piston, from which the appendix 16 extends, to the stem bore whenthe device is positioned on it, hence enabling a pressurized fluidoriginating from the stem to flow between the front surface of thepiston and the dispensing hole Operating the pushbutton causes thecompartment 18 to fill. When the pressure in the compartment 18 is suchas to overcome the resistance of the spring 14 the piston withdraws toits end-of-stroke position and the appendix 16 frees the hole 15 tohence enable the substance to be dispensed. The end-of-stroke positionis shown in FIG. 2; in it can be seen a projection 19 protruding fromthe rear end of the piston to rest against the end of the chamber 3(specifically against the abutment 7) precisely to define thisend-of-stroke position of the piston. Any air which may be presentbetween the rear of the piston 12 and the end of the chamber 3 escapesthrough the air passageway 8 during withdrawal of the piston 12.

It should be noted that the appendix 16 is set and maintained coaxial tothe hole 15 by suitable ribs 20 visible in FIG. 2 and cooperating withan outer surface 16 b of the appendix 16. In the present embodiment theribs are three in number and are disposed 120° apart, but can be of anynumber and can assume any configuration. The appendix 16 also presents aseal portion 16 a suitable to penetrate into the hole 15 to sealedlyclose it, and is connected to the guide surface 16 b by a step 21 whichacts as an abutment and a stop for the piston stroke when the pressurewithin the compartment 18 falls below that provided by the spring 17,consequently the piston advancing to urge the appendix 16 in the hole 15into the closure position. In this situation the fluid within thepushbutton 2 and in the stem interior is isolated from the externalenvironment.

Advantageously the compartment 18 has a considerable volume and apassage cross-section much greater than that defined by the passageways22 and by the stem bore. Consequently the fluid is able, duringdispensing, to slow down considerably within this compartment 18. Thisis very positive particularly when the fluid product to be dispensed isa cream or a foam.

In conclusion it should be noted that the member 11 presents on itssurface an annular projection 23 preferably but not necessarilycooperating with a suitable groove 24 provided in the surface of thechamber 3 for sealedly fixing the member to the pushbutton 2 byinterference.

The assembly of a device conceived in this manner is very simple. Thisis done by inserting the piston 12 into the member 11, mounting thespring about the projection 19 and inserting the combination into thechamber 3.

Advantageously, in the present invention the inner surface of thechamber 3 does not necessarily have to be perfectly cylindrical and canpresent ovalization phenomena, which however do not compromise thefunctionality of the device in question. This is because the seal forthe piston 12 is effected against a part 11 which does not present anyshape irregularities as it is formed in one piece, is easily mouldableand, because of its shape, is easy to form without shape defects orresidual stresses which could lead to ovalizations. The member 11 isfixed to the cylinder both by the annular seat 6 and by the annularprojection 23A provided in its front portion.

In particular, that region of the member 11 involved in the sliding ofthe piston is not used for fixing the piece 11 to the pushbutton;advantageously between that region and the pushbutton a clearance isprovided which does not enable any ovalized walls of the chamber 3 todeform the member 11 in that region.

The alternative embodiment illustrated in FIGS. 3 and 4 is particularlysuitable for use with substances of low viscosity such as deodorantsprays etc., which have to be atomized during dispensing.

Those parts functionally similar to the parts already describedpreviously are indicated by the same reference numerals, and theirdescription will not be repeated.

The pushbutton 2 comprises a member 11 presenting a cylindrical portion11 a from which a frusto-conical portion 11 c extends, connected to afront portion 11 b. A passageway 22 functionally similar to that of thepreceding embodiment is provided in the frusto-conical portion. Thefront portion 11 b in this case has a diameter less than the cylindricalportion 11 a and is inserted into a plug 30 which frontally closes thechamber 3 in which the dispensing hole 15 is provided. The plug 30 isfixed to the member 11 by an annular projection 23A which byinterference sealedly engages those surfaces defining the chamber 3 inwhich a suitable groove 24A is also suitably provided. A hole 31 isaxially provided in the front portion 11 b to act as a guide means forthe appendix 16 (cooperating with its outer surface 16B) and has thesame function as the previously described ribs 20.

Also in this case the appendix 16 presents a peg-like sealing portion16A which besides blocking the dispensing hole 15 provided in the memberis sealedly slidable in a hole 31 provided in the portion 11 a facingthe dispensing hole 15.

Advantageously at the interface surface between the plug 30 and thefront portion 11 b of the member 11 there is provided at least onepassageway 34 communicating with the chamber 3 and arranged toconventionally generate a vortex flow of the fluid to be dispensed.

Again in this embodiment there is provided, in the end of the chamber 3,an escape hole for any air present between the rear part of the piston12 and the end of the chamber 3.

1-15. (canceled)
 16. A dispensing device for fluid substances,comprising: a pushbutton in which a chamber is provided housing apiston, the piston being loaded by an elastic means to urge a frontprojecting appendix thereof into a dispensing hole for the substance, tohence sealedly close the dispensing hole, the pushbutton presenting aseat enabling a hollow stem to be coupled therethrough through which thepressurized substance is fed to the device, wherein in the chamber thereis housed an at least partially cylindrical member in an interior ofwhich the piston slides, in the member there being provided at least onepassageway opening to a front of the piston and communicating with abore of the stem when the device is positioned on the stem, such thatthe pressurized substance originating from the stem, by passing throughthe passageway, is configured to cause the piston to withdraw and hencefree the hole, to dispense the substance, wherein the piston presents afirst sealing lip in proximity to its front portion and a guiding secondlip in its rear portion.
 17. A device as claimed in claim 16, whereinthe piston presents in its rear portion a projection which rests on theend of the chamber when the piston is in its end-of-stroke position. 18.A device as claimed in claim 16, wherein on the end of the chamber anannular seat is provided to sealedly house the member, at leastpartially, and to maintain it in position.
 19. A device as claimed inclaim 16, wherein the member frontally closes the chamber.
 20. A deviceas claimed in claim 19, wherein the dispensing hole is providedfrontally in the member.
 21. A device as claimed in claim 16, whereinthe dispensing hole is provided in a plug that frontally closes thechamber.
 22. A device as claimed in claim 16, wherein the memberpresents guide means for the appendix.
 23. A device as claimed in claim22, wherein the guide means comprises ribs provided in proximity to thehole.
 24. A device as claimed in claim 22, wherein the guide meanscomprises a hole provided in a front portion of the member.
 25. A deviceas claimed in claim 19, wherein in the front portion of the member achamber is provided within which the substance to be dispensing reducesits velocity before being dispensed.
 26. A device as claimed in claim16, wherein the appendix presents a seal portion for closing the hole,and a guide surface cooperating with the guide means.
 27. A device asclaimed in claim 16, wherein the member presents at least one projectioncooperating with the surface of the chamber to sealedly fix the memberto the pushbutton.
 28. A device as claimed in claim 16, wherein the plugcomprises a housing for the member and at least one projectioncooperating with the surface of the chamber to sealedly fix the plug tothe pushbutton.
 29. A device as claimed in claim 16, wherein between theplug and the front portion of the member at least one passageway isprovided communicating with the chamber to generate a vortex movement ofthe fluid to be dispensed.